Underground Construction of Wastewater Lift Station Wet Well

Sealing Wet Well Penetrations on Pump Stations

Underground Construction of Wastewater Lift Station Wet Well

Romtec Utilities designs, manufactures, and supplies pump stations for all types of water in many industries, both private and public. Each pump station we engineer is designed specifically for a single application and site, but there are many commonalities between pump station designs. One source of potential issues is very prevalent in pump stations. That is sealing penetrations in the pump station wet well. There several things to consider when look at sealing wet well penetrations and there are several methods for doing it. Here are a few assessments to evaluate when trying to create effective penetration seals.

Wet Well Penetrations Must Be Installed at the Correct Angle to Function

First, Romtec Utilities does not seal wet well penetrations. This work is a responsibility of the system installer. A penetration can be created in many different methods. The most common penetration is a cored hole in a concrete structure, but these penetrations can be cast/fabricated in-place, sometimes with seals or sleeves. A penetration allows piping and/or electrical conduit to enter or exit the wet well. This is how inlet lines flow into the well and how discharge piping exits it. Electrical conduit penetrations are typically cored onsite and can enter from the top slab with disconnect panels or through a riser with in-ground junction boxes.

Electrical penetrations are typically sealed very effectively due to well-defined code requirements to prevent moisture incursion around electrical components. An onsite electrical contractor makes the final seals on all penetrations and inspects their integrity. This contractor also makes all the final connections as a licensed electrician in the location of the installation. Electrical conduit also commonly enters a well from the top, reducing potential sources for moisture incursion.

Lift Station Discharge Line Being Installed

A much bigger potential source of maintenance issues is with piping penetrations. These issues are almost always a result of improper installation of the pump station. If penetrations are not sealed effectively, pump stations can experience accelerated corrosion, high-levels of I & I, and in some cases leaching or leaking. As part of our pump station package, Romtec Utilities typically always supplies a component called Kor-N-Seal boots. These can be very effective at sealing penetrations when installed correctly. However, Kor-N-Seal boots have a low angle threshold for sealing piping. In other words, pipes that enter a penetration at more than a 7-degree-angle from any direction may create an incomplete seal with the boot. On some job sites, this can be a very small margin of error.

Even though Romtec Utilities does supply Kor-N-Seal boots to installers, we typically recommend that installing contractors “grout-in” penetrations. Using grout creates a more rigid seal, but it is typically more effective and has a lower probability of leaking due to a steep angle for pipes entering the wet well. Ultimately, the choice falls to the installing contractor to utilize the method that they are the most confident will succeed on that installation. The only times this is not the case is when a customer or owner specifies a particular penetration seal. Romtec Utilities has used products called link seals that require a sleeve to be cast-in-place or prefabricated into the penetration. On these jobs, the installing contractor would utilize this specified equipment, but it is still the contractor’s responsibility to install the pump station in the specified way to achieve and effective seal.

Two Concrete Wet Wells Being Constructed Adjacent to Each Other

Pump station penetrations can be a source of ongoing issues if they are not created correctly. Romtec Utilities provides as much engineering, equipment, and advisory support as possible to ensure a good seal on all penetrations, but our crews do not actually do the installation work that will create the seal. For customers and owners, meeting with your contractor to discuss the wet well penetrations and seals is a good “best practice” for getting the best Romtec Utilities pumping system. If you have any questions about this subject or about sealing equipment, give us a call or send us an email because all we do is pump stations.

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